Flashing black screen on booting Win10 laptop

[t4akawolf]

Hello, when I try to boot up my laptop, it gets past the manufacturer logo (VAIO in my case), then when it should be showing me W10's booting screen it just continuously flashes a black screen (on 4 seconds, off 2; approximately). No cursor in the corner.
[video="https://www.youtube.com/watch?v=3ln_qkqWvC8"][/video]
I can boot into Assist mode (manufacturer's inbuilt troubleshoot/recovery environment) and I can boot into the installation screen with W10 installation media.
What's wrong?

 

[t4akawolf]

Anybody?

Could it be a memory issue?
It's 4gb onboard.

This problem started after I opened her up to fix this display cable problem I've been having for a year or so now where the screen will sometimes start flickering when I tilt it in either direction. What I usually do when it gets very bad is open the back panel, gently tweak/adjust the display cable that goes in through the hinge, close the panel, and voila no more flicker when I tilt back or forth (at least until my adjustment loosens or whatever). When the problem comes back, I repeat, with success.
This time, though, I decided to try and more permanently hold the cable in an optimal place by wrapping Scotch tape around it, then gluing the tape (because it wasn't strong enough by itself) to this plastic thing around what I'm fairly certain is the RAM (I'm adding pictures to the original question). Then I placed a folded piece of paper over the thing for added stability, then I put the panel back on, screwed it in, tried booting, and it showed me the VAIO logo (no flicker, so at least that worked) but then it seems to take a super long time to boot (which it kinda always has done, because it's an older laptop, but never this long) and that was when I noticed the blackscreen on-off thing.